Tire Bead
The inner edge of a tire containing steel wires that seats tightly against the wheel rim to create an airtight seal.
The tire bead is the thick, reinforced inner loop of the tire that makes contact with the wheel rim. It contains high-strength steel wires wrapped in rubber and fabric, forming a rigid ring. The bead's job is to sit tightly inside the rim's bead seat, anchoring the tire to the wheel and creating an airtight seal that holds tire pressure.
During tire mounting, specialized tire machines stretch the bead over the rim flange. A soapy lubricant is applied to help the bead slide into place, and compressed air is used to expand the tire until the bead 'pops' into its seat on the rim.
If the tire bead is damaged or torn during mounting, or if the rim is corroded or bent, air will leak slowly from the bead seat. Debris trapped between the bead and the rim can also cause slow leaks. A technician can clean the rim surface and apply bead sealer to resolve minor sealing issues.